Electric phonograph apparatus



NOV. 28, 1933. Q M DUNNlNG 1,937,268

ELECTRIC PHONOGRAPH APPARATUS INVENTOR,

BY LA', ATTORNEY Nov. 28, 1933. Q M DUNNlNG 1,937,268

ELECTRIC PHONOGRAPH APPARATUS Filed Sept. 18, 1931 2 Sheets-Sheet 2 INVENTOR 'a M. PWM? BY A ATTORNEY Patented'nNov. l2.8, 1933 1 Y 1,937,268.L

UNirs STATES, PATENT oFFlcr.

vELECTRIC PHONOGRAPH APPAim'rUs Orville M. Dunning, East Orange, N. J., assignor to 'llhomasV A. Edison, Incorporated, West 0r-v ange, J., a corporation of New Jersey Y Application septemimrl 18,1931

Serial No. 563,468 Y 19'Claims. (Cl. 179-100.41)

This invention relates to electric phonograph It is still a further objectrof this invention to apparatus for recording and reproducing sound, provide apparatus of the class-described in which andmore'particularly to the construction of the the Weight effective on the stylus, andthe presrecording and/or reproducing units employed for sure of the stylus on the record, may be controlled cutting a sound track in the record and trans- Within Wide limits. i l 60 forming therecorded sounds into electrical cur- Still other objects and advantages of Amy inrents.` vention YWill beapparent from the specification.

While my invention is applicable to any type In accordance with the preferred embodiment of phonograph apparatus, it is of particular utilof my invention, I provide a novel construction ity When used in connection with phonographs offarmature and mounting therefor, togetherwith 65 employing a cylindrical Vrecord and more espeassociated parts so arranged that the armature cially in'phonographs of the commercial dictatis very much shorterthan those customarily eming machine type.` V- ployed in apparatus heretofore used, and has a Asis Well known, the records used with com- Very much smaller moment of inertia, providing mercial dictating machines are ordinarily shaved for considerably improved recording and repro- 70 after using, and used again and again.. whereby ducing of the relatively higher voice frequencies the thicknessy of the records in use may vary to Which serve to impart clarity and definition of a considerable extent. In addition to the variaarticulation to the recorded and reproduced tion in thickness of the record'already referred to,V sounds. Secondly, I so arrange these parts that there may be slight irregularities in therecord the armature and its mounting are the only parts 75. itself or in its mountingV which -Will tend tocause which are carried by the record and are entirely. movement of the stylus as it rests upon the sur-l free to rotate to permit the stylus to rideI upon face ofthe record during its rotation. the surface of the record and tofollow irregulari In recording sounds with apparatus of this type ties thereof, Without changing the uX distribu- 'one of the diiculties'istoso'i arrange the recordtion through the coils. Thirdly, I mount the 804 ing apparatus that the recording stylus Vmakes a armature flexibly and resiliently upon its mountcut of a predetermined depthrin the record. In ing in such a Way that the armature is yieldingly recordings of the hill and dale type consider-v maintained in neutral position, as regards moable difficulty may be met in causing the recordtions which vary the reluctance of the air gap.

ing stylus to cut the correct' depth, because of By these features, Which Will hereinafter be 85` irregularities andlack of uniformity in the didescribed more in detail, the mass of theappa.- ameter ofthe record.' V i ratus which is effective on the record andwhich Another difculty encountered is lackof qualmust be moved thereby is maderelatively small ity of the recording and of subsequent reproducandthe high frequency response is improved.

vtion due to the fact that most recording units The features of novelty which I believe to be 9 0` which are suitable for use `on commercial dictatcharacteristic of my invention are set forth withl ingmachines do not properly record the high fre, particularly in the appended claims. My inquencies Which impart clarity and denition of vention itself, however, both as to its fundamental articulation. principles, and as to its particular embodiments 40 t In accordance With'the present invention I have will best be understood by reference to the specifi- 95VA provided apparatus Which 'is particularly intendcation and accompanying drawings, in which like ed to overcome the difficulties abo-ve referred t'o reference characters represent like elements, and

as well as others. g in which: r l

It is an object of this invention to provide im- Fig. 1 is a side view of one type of recorder proved apparatus for recording and reproducing unit embodying the invention; Y loo on a record 'With minimum distortion. n Fig. 2 and 3 are end and top views, respectively,

It is a further object of the invention to pro-A of the Same unit; vide a recording and reproducing unit which will Fig. 4 is a detail view of the armature suspenv record and reproduce sounds with fidelity on sion ofthe unit of Fig. l; y records varying in size, especially when used by Fig. 5 is a modification of the adjusting struc- 105 lay operators. I ture for the recording unit;

YIt is a further object of my invention to pro- Fig. 6 is a side view of another form of revide apparatus ofthe class described Which will corder unit embodying the invention, the suprecord and reproduce speech with improvedclarporting plate and arm for such unit being ornit- 110 ity and articulation. ted; and

Fig. i is a sectional view taken on line 7-7 ci Fig. 6 but showing the supporting plate and arm.

Referring particularly to 1, 2, 3 and 4, a portion of a carriage structure 5 of a common form of dictating machine is shown with a stop 6 to limit the movernen+ oz" an arm 'l pivoted at 8. The arm l supports and carries the entire recording unit, which comprises a pair of coils 9 and 10 through which pass magnetic core roem.- bers 12 and 13. lThe upper portion ci the core members 12 and 13 are joined by a yoke i4, while the lower portiois converge to form pole pieces 12a and 13a deng an air'gap 16. The4 ends of the pole pieces 12a and 13a are cutaway in cylindrical form. A magnet 13 (Fig. 3) which may be vin the forni of a U, has one pole abutting against an L-shaped 19 of magnetic material which is attached to the'yole 14. The other pole of the magnet ahuts a member 21 of magnetic material which connects with a U-shaped memtacting with and suitably secured to a pair of supports23 and 24 of magnetic material in which are threaded pivot screws 26 and 27. i yoke 30 is mounted for pivotal movement on screws 26 and 27, this yoke having spaced projections 31 carrying a shait SEonv/'b'ch armaturer 34 and par s associated therewith are mounted.

The armature 34 has a cylindrical had, whicr is disposed within the cylindrical air gap 16 with the axes of the air gap and oi the armature head coinciding. The armature is pivoted on the shaft 32. An extension arm 3ft-A secured to the armature 34 is fastened at its outer end to the diaand the diaphragm 35 for damping the armature motion, or oil or other Vviscous material be provided-and conned betweenthe diaphragm and cover. The centering unit -36 is maintained in a xed position with respect Yto the armature 34 by being mounted on the yoke 30 as by'v an arm 40, so that the centering unit 36, armature 34 and yoke 3G move as a unit about an axisthrough the pivot points 26and 27. This axis passes through the centre of the cylindrical armature head positioned in the gap 16 so that members 23 and 24, from w.

yoke 30, through the projections 31 to the arma-- rotation of the armature assembly may take place' without changing' the flux distribution through the coils 9 and 10. Thearrnature 34 may carry at its extremity a stylus 41 which contacts with the surface of a record 42. 40 may he cut away'to provide an opening for the passage of arm34-A- The magnetic circuit may he traced from the L-shaped member 19 at one pole of the magnet 1 8 through the magnet, through the vertical member 2l, through `the U-shaped member dividing, and passing then along the vertical :l it passes tothe ture 34, where the two magnetic paths unite,

through the air gap 16, the two pole pieces 12a.

and 13a to the yoke 14, making contact with the L-shaped member 19. The yoke 30 and supports 23 and 24 are positioned as close together as is consistent with free rotation of the armature assembly and the same condition obtains where the armature 34 is pivoted to the Vyoke on the projections 31. The narrower these gaps are made, the more sensitive the apparatus wllhe.

g all The coils 9 and 10 are wound and connected s6' that passage of current therethrough increases the fluX flowing in one core branch and decreases it in the other, thereby causing the armature to swing about axis 32. In reproduction, such movement of the armature generates currents in the windings of the coils 9 and 10 by causing a shift in the flux from one core to the other. It will be noted that the two pole-pieces 12a and 13a are of the same magnetic polarity, instead of opposite, as is usually the case.

In the operation of the apparatus, it will be observed that any irregularities in the surface of the record 42 Will rotate the entire armature assembly about an axis passing through adjusting screws 26 and 27 and the head of the armature. This rotation, however, does not change in any manner the position of the armature head in air gap 16 with respect to pole pieces 12a and 13a, the position of the armaturehead being controlled. by 'the restoring diaphragm 35 inthe unit 36. It will be 'understood that this centering means 36 may be .replacedby springs, rubber blocks; or other likedevices well known in `the art. l

vThe stylus is vibrated for recording, by variations in the i'lux through pole pieces 12a and 13a which attracts the head ci the armature, causing itjto oscillateabout the axis 32. Should the armature structure exert too vsmall or'too great a pressure von the record, it may be counterbalanced about the pivots 26 and 2'7 by the provision of counterbalancing means similar to that employed.

in the recorder unit shown in Figs. 6 and 7. If desired, the restoring unitV may (as inthe case of the apparatus shown in Fig. 5) be provided with a bracket and oneor `more weights may be provided to be positioned thereon, whereby Weight may be added for reproducing and removed for recording. Y

1t will be seen that the structure just described permits the s'tylus'to" swing freely up and down over irregularities in the record and permits considerable variation in the size of the records, without interfering with the operation. of the armature. 7

Referring now toV 5, a modification of the apparatus is' shown. The arm 45 which carries Vthe'apparatus is pivoted at 46 freni-the carriage 47 'out in thiscase is provided with the arm 14 having an advance ball 43 .which ridesy on .the

record surface 40 in advance ,of the cutting stylus. In this arrangement there is no stop for imiting downward movement of the arm 45, as inA Fig. -1 V The storing unit 36 of the apparatus shown in Fig. 5 is provided with an angular resilient bracket or arm secured at one end to the unit hy a screw 91, arm being adapted to Temgvaigly hold a weight 32 in positionon the unit. When the apparatus is to be used for reproducing, the weight .92 is appliedto the unit, as-shown, but when' such'apparatus is to be used for recording, such weight is removed. 1t is desirable to provide a nun'lherof different sis-ed weights, similar to weight 92; so that'when `the apparatus is kbeing used for reproducing, the

pressure of the stylus on the record surface may ce regulated asfdesiredby applying to the restoring unit 36 a weight 92 of proper size.

The apparatus shown in Figs. 6 and l illustrates the'application of my invention to the usual icrin ci. magnetic circuit well Known in ce art, in which an armature is located in an air gap between pole pieces y.having opposite polarities, In this apparatus a plate 50 serves Yio f magnet. l

The remaining structure of .this recorder is .to support and hold in place'the, various parts of vthe apparatus. To theA plate 5G is fastened an .arm which is pivoted at. 61 on carriage `62 4which is fed across the face of the record in any kinner adjacent ends of which are slightly spaced and define a cylindrical air gap 55 surrounding the cylindrical head portion of an'armature 56. The head portion of the armature 56 is cylindrical in cro'ss section and the two pole pieces are concentric with this portion of the armature to permit the armature to be rotated about an yaxis passing through the center of the air gap without changing the fiuxdistribution through the air gap. The pole pieces 52 and 53 are provided with adjustable pivots 64 and 65 which allow rotation of the armature support, which is a U member having arms 67. Y These pivot points are arranged in line with the axis of the head of the armature 56 so that rotation .of the armature assembly on pivots 64 and 65 will not varythe air gap or the reluctance Aof the magnet circuit.

The two arms 67 arel of magnetic material and are provided with two bosses rextending therefrom in which a shaft 58 of non-magnetic material passes. This shaft also passes through an 'enlargedportion 56a of the-armature which is free to oscillate about the'axis of said shaft independently ofthe rotation of the armature 'place by means of a bracket ofnon-magnetic"A material 70 which constitutes the base of the U member above referred to and which also is provided with an integral angular portion '72 for fastening the arms o7 to the centering .andrestoring unit '71. A small air gap is maintained on either side of the enlarged portion 55aof the.

armature 56 to prevent.shorticircuitingfof the similar to the embodiment shown in Fig.` i, in that' an arm "Mis fastened `to the armature 56 at its enlarged portion 56a. Thisarm carrios'at its outer end a stylus '75 which makes contact with the Vrecord surface 75, and said Yarm is connected vtoa diaphragm 78 mountedin the unit 71. The diaphragm 'Z8 operates in the 'same manner as that in the unit shown in Figi l, and a screw cover 80 is provided for tightening the diaphragm within the threaded portion 79. The diaphragm and associated parts constitute Ymeans for holding or restoring the armature to its central position in the air gap when it has 1eeen disturbed.

The free movement of the stylus and armature assembly without disturbing the magnetic circuit of the entire system is provided for by the pivots 64 and 65 which permit the arma-tine assembly to rotate about a line passing through the cylindrical head portion of the armature. The armature structure may be weighted (in the manner shown in Fig. 5) or may be counterbalancedabout the pivots 64 and 65. In order to so counterbalance the armature structure, one

i said rst axis.

Y,of thev arms 6'7 of the Ufmember referred vto above, is provided with a rod which extends through an opening in the plate 50 and carries a weight. 96. The weight 96 is mounted on rod 95 so as'to be adjustable as by being threaded thereon.`

It will be noted -while the armature is vibrating at sound frequencies, its vibrations are transmitted to the centering member and hence react on the armature support. In order that the armature support shall remain stationary for vibrations of sound frequency, the mass and -moment of inertia of the armature is kept low with respect to that of thearmature support.A While I have shown and described certain preferred embodiments of my invention, it will be understood that modifications and changes may be made withoutVV departing from the spirit and scope of my invention, as will be understood by those skilled in the art. l

I claim: v 1. In phonographic apparatus, in combination, v a magnetic circuit, an armature disposed in a gap in said circuit for vibration therein, and a support for the armature mounted for movement about an axis passing through the armature, .the armature .being mounted on said support for movement about another axis passing through the armature. i

2.r In phonographic apparatus, in combination, 1 a magnetic circuit, an armature disposed in a gap in said circuit for vibration therein, and a support for the armature mounted for movement about an axis passing through the armature, said armature being mounted on said sup- 1 port for movement about another axis parallel to said first axis and passing through the armature. l Y 3. In phonographic apparatus, in combination, a magnetic circuit, an armature disposed in a 1 gap in said circuit and a support for the armature mounted for movement about an axis passing through said gap, s aid armature being mounted on said support for vibration at sound frequencies about an axis without said gap. 1

4. In phonographicapparatus, in combinationa magnetic circuit, comprising spaced pole pieces providing an air gap, an armature disposed in .said gap, and` a support for the armature mounted for movement about an axis which is 1 fixed with respect to said pole pieces, said armature being mounted on said support for movement about an axis spaced fromv and parallel to 5. In phonographic apparatus, in combination, a magnetic circuit, an armature positioned in a gap in said circuit, and means for yieldingly supporting said armature centered in said gap for oscillation therein, said. means-being free to rotate about an axis central ofsaid gap.

6. In phonographic apparatus, inY combination, a magnetic circuit, an armature positioned in a 'gap in said circuit, a support for engaging said armature to permit Vibration thereof while maintaining the position thereof, said support in a gap 'in said circuit, and a support for said 145 armature, said support lhaving said armature pivotally mounted thereon, and said support being pivotally mounted on an axis intersecting the head of said armature.

8. In phonographic apparatus, in combina- '.tion, a magnetic circuit, an armature positioned ina gap in said circuit, and a support for said armature, said support being formed of magnetic material and forming a part of said magnetic circuit, said armature being mounted for vibration on said support, and said support being mounted for swinging movement about an axis intersecting the head of said armature and parallel to the vibration axis thereof.

9. In phonographic apparatus, in combination, a source of magnetic potential, a magnetic circuit therefor comprising a pole piece having two branches of like polarity and having a gap therebetween, a coil associated with at least one oi said branches, an armature'having a head positioned in said gap, and a support of magnetic material, said armature being secured to said support for vibration, said support being mounted for swinging movement on an axis parallel to the vibration axis of said armature and passing centrally through the head of said armature, said armature and said support forming a part of said magnetic circuit and being of opposite polarity from said pole pieces.

10. In phonographic apparatus, in combinaftion, a magnet, a magnetic circuit therefor cointion of a magnetic circuit having a plurality of branches, and deiining an air gap in said magnetic circuit, coils positioned onfsaid branches, an armature positioned in said air gap, said armature being pivoted at a point removed from said air gap, a stylus mounted on said armature for engaging a record, and means Vfor mounting said armature for rotation about the center of said air gap independently of the motion of said armature within said air gap. Y

12. In phonographic apparatus, a magnet,` pole pieces associated with said magnet and deiining a cylindrical air gap, an armature having a cylindrical head portion for operating in said air gap,

said armature being' pivoted at a point removedv from said air gap, a stylus mounted on said armature, means for restoring said armature head to the center o said air gap when vremoved therefrom and means for mounting said armature assembly and restoring means for rotation about an axis passing through the center of said` air gap and said armature head portion.

13. In phonographic apparatus," in combination, a magnetic circuit, pole pieces associated therewith and defining a cylindrical air gap, a

support mounted for rotation about an axis coincident with the axis of said air gap, an armature pivotally mounted on said support for vibration and having a cylindrical head portion normally Apositioned concentrically in said gap, and yielding centering means mounted on said support and associated with said armature.

14.111 phonographic apparatus, in combina'- tion, a magnetic circuit, pole pieces associated therewith and dening a cylindrical air gap, a support mounted for rotation about an axis coincident with the axis of said gap, an armature secured to said support for vibration thereon and having a cylindrical head portion normally centered in said gap, flexible and resilient centering means mounted on said support and a connection between said armature and said centering means.

15. In phonographic apparatus, in combination, a record, a carriage movable relatively thereto, an electromagnetic translating unit mounted on said carriage, an armature support pivotally secured to said unit for swinging movement toward and away from said record, and an armature vibratably mounted on said support.

Y16. In phoncgraphic apparatus, in combination, a record, a carriage movable relatively thereto, an electromagnetic translating unit mounted on said carriage, an armature support pivotally secured to said unit for swinging movement toward and away from said record, an armature vibratably mounted on said support and a centering device mounted thereon in operative relation to said armature.

Y 17. In phonographic apparatus, in combination, a vibratile armature, a stylus connected to said armature for engaging a record, a swingable support for saidarrnature movable toward and away fromsaid record about an axis intersecting'said armature, and means lfor controlling the pressure of said stylus on said record.

18. In phonographic apparatus, in combination, a vibratile armature, a stylus connected to said armature for engaging a record, and a swingable support for said armature movable toward and away from said record about an axis intersecting said armature, the mass of said armature being small with respect to the mass of said armature support.

19. In phonographic apparatus, in combination, a vibratile armature, a stylus connected to said armature for engaging a record, a swingable support for said armature movable toward andaway from said record about an axis intersecting said armature, the moment of inertia of said armature being small with respect toA that of the armature support. 

